1. Field of the Invention
This invention relates to methods for detecting and diagnosing epithelial cancer.
More particularly, the invention relates to a cancer detection method employing video technology for real-time examination of potential cancerous sites on the epithelium, combined with comparison of a digitized image of a suspect site with digitized images of known cancerous and non-cancerous sites, to effect a diagnosis of the suspect sites.
In another aspect, the invention relates to real-time videographic examination techniques in combination with in vivo tissue staining techniques and with digitized image techniques for the diagnosis of epithelial cancer.
In an even further and still more particular respect, the invention relates to cancer detection/diagnosis techniques in which videographic records of the visual image of a suspected cancer site on the epithelium are compared with a real-time videographic image of the suspected site which is made at a later time.
In a further aspect the invention relates to cancer detection/diagnosis techniques in which digitized videographic images of a suspected cancerous site on the epithelium is compared with digitized images in a data base containing images of both cancerous and non-cancerous epithelial lesions.
2. Description of Related Art
Visual examination of epithelial tissue to detect cancerous or pre-cancerous tissue is known. In vivo examination of suspected cancerous sites using standard photographs, magnification by an operating microscope (stomatoscopy) and color photomicrographs for the detection of oral cancer was described in the article by Shedd, et al., American Journal of Surgery, Volume 110, pages 631 et seq. (October 1965).
Dental television cameras which facilitate visualization of the oral cavity are also well known. See, e.g., the U.S. Pat. No. 4,260,376 to Litel; U.S. Pat. No. 4,195,626 to Lemmey and U.S. Pat. No. 5,251,023 to Cooper. Apparatus and methods for recording in vivo holograms and for reconstructing such recorded holograms for later display on a television monitor were described by Bjelkhagen. et al. in U.S. Pat. No. 5,014,709.
The use of biological stains for in vivo selective delineation of cancerous and pre-cancerous tissue is also well known. See, e.g., U.S. Pat. No. 4,321,251 to Mashberg and the article by Nibel (Journal of American Dental Association, Volume 35, pages 801 et seq. (June, 1964)). Shedd, supra, discloses the use of selective tissue staining techniques in combination with stomoatoscopy.
Cancer of the oral mucosa is one of the leading terminal diseases causing thousands of deaths annually in the United States alone. Oral cancers occur at various places in the oral cavity, including the floor of the mouth, the anterior pillars, on the pallet and on the bottom and the dorsum of the tongue. Most oral cancers are curable by surgical excision if detected early enough. However, the difficulty of visualizing the various intraoral epithelial surfaces makes it difficult to detect oral cancers in the very early stages. It is particularly difficult to detect pre-cancerous sites in the oral cavity, because of the difficulty in visualizing the physically remote oral epithelium coupled with the confusingly similar appearance of precancerous tissues with tissue having other, non-cancerous conditions.
While video technology and equipment has been available for a number of years which enables dental practitioners to visualize intraoral tissue in order to facilitate conventional dental procedures and while tissue staining techniques have been known for many years which selectively stain and visually delineate cancerous epithelial tissue and plaque and while photographic, holographic and other techniques have been known for recording visual images for later examination, such techniques have not been effectively employed to provide straightforward real-time diagnostic visual examination of the intraoral epithelium for detection of oral cancers and pre-cancerous conditions.
It would be highly desirable to provide improved methods for detecting epithelial cancers, particularly oral cancers.
It would also be advantageous to provide such methods which can be effectively employed by general dental practitioners as a part of routine dental procedures or xe2x80x9ccheck-upsxe2x80x9d or as an adjunct to routine periodic dental office visits for plaque removal and the like. Such improved oral cancer detection methods could result in early detection of oral cancer and timely therapy, saving many thousands of lives annually.
Accordingly, the principal object of the present invention is to provide an improved method for early detection of epithelial cancer, particularly oral cancers, including single or multiple small or large sites.
Yet another object of the invention is to provide such improved methods which can be used effectively by general dental practitioners, with a minimum of additional training and expense, to provide routine oral cancer screening services as an adjunct to routine dental procedures and examinations.
Still another object of the invention is to provide oral cancer screening techniques which permit real-time examination of remotely located epithelial tissues in the oral cavity, which are difficult to examine by conventional visual examination techniques.
Still another and further object of the invention is to provide real-time cancer detection techniques which, nevertheless, provide a permanent record of the results of such an examination, so as to permit comparative examination of the present image of a suspected cancer site with images of the same site made at an earlier time.
A still further object of the invention is to provide an epithelial cancer detection and delineation method which provides a visual record for later reference during therapy, e.g., to aid in excision surgery.
Yet another object of the invention is to provide a method for determining whether a suspected cancerous site on the epithelium is cancerous or non-cancerous, employing a comparison of a digitized videographic image of the suspected site with digitized images known cancerous and non-cancerous epithelial lesions.